Using contouring and even more advanced techniques can create a theatrical "makeup" that doesn't look like "makeup".

This is the same as how characters on a TV show might wear makeup to make them look much older for a flash forward or other such episode - that's "makeup", too - but most people would never saw, "wow, they're wearing so much makeup" because it's made to look like an accurate representation of how the person would look older. Example.

You probably also don't think about how the men in movies and TV shows are wearing makeup because it doesn't look like makeup - yet it has an impact on how they look.

The same applies to "youth" makeup. Once you start to use makeup for more than just "make up" you open up so many more possibilities. Youth makeup can only go so far without prosthetics to fill out lost fat, but you can still do what you can without it by making informed choices - and at least avoiding anything that will make you look older. Youth makeup is common in things like the Harry Potter movies and Game of Thrones where actors hired as kids started to "outgrow" their parts or for flashbacks. And it's not just makeup, it's other choices, too.